Interpretive Summary: Steroidal glycoalkaloids are naturally occurring plant metabolites that are found in foods, including potatoes and tomatoes. Their content in plants is controlled by both genetic and environmental factors. Glycoalkaloid profiles can be passed to progenies during breeding and hybridization of wild and cultivated potatoes designed to develop improved potatoes. In honor of the designation by the Food and Agricultural Organization of the United Nations (FAO-UN) of 2008 as ‘The Year of the Potato’, we participated with Korean and Japanese scientists in a study on the distribution of glycoalkaloids in 59 accessions of two wild and five cultivated Solanum species originating from the Centro International de la Papa in Peru. The results suggest that to create new health-promoting potatoes, breeders should attempt to cross accessions of Solanum acaule with the highest tomatine content (acl-D-1 and acl-D-3) with accessions containing low total amounts and low ratios of a-chaconine to a-solanine. These include Solanum andigena T-AY-46-1 and T-AY-2-2. This is because published studies showed that nontoxic tomatine protected rainbow trout against carcinogen induced tumors, reduced plasma cholesterol and triglyceride levels in hamsters, stimulated the immune system in mice, and inactivated pathogenic viruses. Orally fed potato glycoalkaloids protected mice against lethal infections by Salmonella typhimurium via stimulation of the immune systemn. It may also be worthwhile to include in breeding programs accessions of Solanum curtilobum and Solanum juzepczukii that contain the disaccharide dihydro-beta1-chaconine, described here for the first time.

Technical Abstract:
Steroidal glycoalkaloids are naturally occurring, secondary plant metabolites that are found in foods, including potatoes and tomatoes. Their content in plants is controlled by both genetic and environmental factors. Glycoalkaloid profiles can be passed to progenies during breeding and hybridization of wild and cultivated potatoes designed to develop improved potatoes. The most common potato, Solanum tuberosum, contains primarily the glycoalkaloids, a-solanine and a-chaconine. However, wild-type potatoes being used for breeding new varieties contain other, less common glycoalkaloids. Because glycoalkaloid composition is a major criterion for the release of new potato cultivars, we used HPLC, TLC, GC, and GC–MS to determine their nature and content in several Solanum species widely used in potato breeding and hybridization programs. Solanum tuberosum, as well as S. andigena and S. stenotomum contained a-solanine and a-chaconine. S. canasense was found to contain only dehydrocommersonine. S. acaule contained a-tomatine and demissine. S. juzepczukii and S. curtilobum contained demissine and two previously unidentified glycoalkaloids. We characterized them as demissidine-glucose/rhamnose (1/1 ratio) and demissidine-galactose/glucose/rhamnose (1/1/1 ratio), tentatively named dihydro-ß1-chaconine and dihydrosolanine, respectively. We found extensive variability in the glycoalkaloid profiles in the tested potato varieties. The possible significance of these findings for plant breeding and food safety is discussed.